What do you mean by a century-old song, confidant and masterpiece?

It means that a good musical work can last forever, transcend time and space, and be remembered forever. It can make people forget the troubles of the world and feel the purification and sublimation of the soul. Behind this sentence is a high praise and admiration for music art. A century-old poem of bosom friend, a masterpiece, is a poem, and it is the first elegant poem of Qin Dynasty among the eight elegant poems of life, that is, "Qinqi painting, calligraphy, wine and tea". The author has no way to prove it.